FR2572446A1 - FLOOR SYSTEM FOR SEISMIC INSULATION. - Google Patents

Abstract

A) FLOOR SYSTEM FOR SEISMIC INSULATION. B) FLOOR SYSTEM FOR SEISMIC INSULATION COMPRISING A FLOOR ARRANGED ABOVE A FOUNDATION, A CERTAIN NUMBER OF SUPPORTS16 ALLOWING THE FLOOR TO MOVE HORIZONTALLY AND A CERTAIN NUMBER OF GROUPS OF TWO RETURN ASSEMBLIES26 AND 28 IDENTICAL AND ARRANGED PERPENDICULARLY L 'TO ONE ANOTHER. EACH RETURN GROUP HAS TWO SLIDES42, 44 WHICH CAN MOVE TOGETHER OR MOVE AWAY, HELICAL TENSION SPRINGS54 ANCHORED BETWEEN THE SLIDES TO CONNECT THEM TO EACH OTHER, A CERTAIN NUMBER OF STOPPERS60 TO PREVENT THE SLIDES FROM MOVING APPROACH TOO CLOSE TO EACH OTHER AND TO THE CONTACT ELEMENTS62 FIXED TO THE FLOOR AND PROVIDED TO COME INTO CONTACT WITH THE SLIDES TO MOVE THEM ACTING AGAINST THE RETURN FORCE OF THE SPRINGS. C)THE INVENTION ALLOWS TO CREATE A PARTICULARLY RELIABLE ANTI-SEISMIC FLOOR SYSTEM.

Description

1 Z> o2572446

  FLOOR SYSTEM FOR SEISMIC INSULATION.

  The present invention relates to a floor system for seismic isolation showing a proper seismic isolation function with respect to a vibration or an external force such as an earthquake. Electronic computers and generators for emergency situations, for example, as well as hazardous materials, such as dynamite and chemicals, are easily

  susceptible to an adverse influence caused by what is said above

extra.

  Such devices, equipment or packaging for

  contain dangerous materials must be effectively protected.

  To protect such vibration-sensitive and dangerous devices and equipment from external vibration, we have

  conventionally, adopted two countermeasures listed below.

under in detail:

  The first countermeasure is to study correctly

  the equipment itself or the equipment to contain such equipment

  dangerous in order to increase their rigidity and increase their frequency

  this natural so as to avoid a possible resonance at the frequency of the external vibration. However, the first countermeasure involves

  expensive equipment or equipment and is not practical.

  The second countermeasure consists in providing a seismic isolation function to a floor on which are installed

  different devices sensitive to vibrations. A number of

  resilient seismic insulation housings are housed between a floor and a foundation that resiliently supports the floor. A system for seismic isolation, including the elastic elements, the floor and the devices or equipment that are placed on the floor, is set at a very low natural frequency, thus avoiding the resonance of the system with respect to the external vibration. Since, according to the second countermeasure, the external vibration can be absorbed by the elastic elements, only a damped vibration is actually

  transmitted to appliances or equipment on the floor.

  Therefore it is not necessary to provide a corresponding rigidity

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  for appliances or equipment. As a result, the cost of appliances or equipment is not higher than in the case

of the first countermeasure.

  U.S. Patent No. 4,371,143 discloses a floor system for seismic isolation as an example of carrying out the second countermeasure. The known floor system comprises a number of apparatuses which exhibit a seismic isolation function and are arranged between the floor and the foundation. Explained in more detail, the seismic isolation apparatus has a plate-shaped base disposed on the foundation, a plate-shaped support disposed on the base so as to be slidably movable in a horizontal direction and coupled to the base. lower surface of the

  floor, as well as earthquake-proof supports to support elastic-

  support in relation to the base. Here the antiseismic support comprises an elastic element which encloses the outer peripheral portion of the support and which is provided to tighten the support, from the outside, with

  a predetermined force, as well as stop elements fixed to the

  to allow regulation with regard to a displacement in

  a direction in which the elastic element contracts.

  Accordingly, in the normal state, the support is maintained on the base in a predetermined position. Explained in more detail, the resilient member has four tension coil springs disposed along respective sides of the support and four connecting members connected together to the tension coil springs.

respectively.

  In accordance with the seismic isolation floor system, if a vibration force exceeding a tension force initially given to the helical coil springs is transmitted

  to the apparatus for seismic isolation, because of, for example,

  earthquake, the support and therefore the floor moves

  cent in the horizontal direction by acting against a restoring force of the helical tension springs. That is, the vibrational energy of the earthquake is stored in the springs

  helicoidal tension, thus damping an effective vibration force.

  transmitted to the device on the floor.

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  According to the floor system mentioned above, however, if there is a break in one area of the resilient element surrounding the support of a coil spring, the element

  elastic is completely failing to perform its own function.

  It is therefore impossible to show the seismic isolation function mentioned above. It also has the disadvantage that, if a rotating force acts in a horizontal direction on the floor under the action of vibration resulting from an earthquake, it is not possible to effectively reduce the rotation movement of the floor. Suppose now that a number of seismic isolation devices are arranged in a matrix, between the foundation and the floor. In this case only

  seismic isolation devices which are located close to the periphery

  The exterior of the floor effectively serves to suppress the rotational movement of the floor. Explained in more detail, a force acting on the respective seismic isolation apparatus, if the floor tends to pivot about a center, corresponds to a torque represented by the product of the rotational force by the distance between the center and the apparatus for seismic isolation. Therefore, it is the voltage springs of the seismic isolation apparatus that are located closest to the outer periphery of the floor that serve the most

  effectively to suppress the rotational movement of the floor.

  In addition, of the four coil tension springs of the seismic isolation apparatus, only a coil spring tension closest to the outer periphery of the floor acts most effectively to suppress the rotational movement of the floor. Although a number of seismic isolation devices are planned under

  the floor, it is not possible to effectively remove the movement

  rotation of the floor and thus to obtain a better insulation effect.

earthquake.

  Because the four coil tension springs are bonded to surround the support, the known seismic isolation apparatus becomes more cumbersome and complex due to the presence

  four coil tension springs.

  It is therefore an object of the invention to provide

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  a floor system for seismic isolation that can effectively perform a seismic isolation operation with reliability

  high and can be compact.

  The aforementioned object of the invention is achieved by the seismic isolation floor system discussed in more detail below. The floor system of the invention comprises a floor disposed above a foundation, with a space between them and on which is placed an object that must be isolated by damping the seismic effects. Supports are arranged between the foundation

  and the floor to support the floor so that it can move

  in a horizontal direction. A number of return devices are disposed between the foundation and the floor so that when the floor moves in the horizontal direction from its initial position relative to the foundation, the return devices act effectively to bring the floor to return to its original position. The respective return device comprises a first return assembly and a second return assembly. The first return assembly comprises two first movable elements arranged on one of the two, the upper surface of the foundation and the

  lower surface of the floor, 'and able to move in a direction

  horizontally, to get closer and move away from each other;

  first stop means to prevent the first two

  movable parts do not move within a predetermined distance in the direction of each other; first spring means

  voltage to connect the first two movable elements to each other.

  the; and the first contact elements provided on the other of the two / the upper surface of the foundation and the lower surface of the floor, and adapted to, if the floor moves in the horizontal direction relative to the foundation, to come to contact with one of the first movable members to allow this first movable member to move away from the other movable member by acting against a

  return force of the first tension spring means.

  On the other hand, the second return assembly comprises two second movable means provided on one of the two, the upper surface of the foundation and the lower surface of the floor,

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  and movable to move closer and away from each other in a second horizontal direction perpendicular to the first horizontal direction, second stop means to prevent the second movable means from moving to come to less than a predetermined distance in the direction of one another> second tension spring means for connecting the two second movable means to each other and second contact members provided on the other of the two , the top surface of the foundation and the bottom surface of the floor, and adapted to, if the floor moves in the second horizontal direction, come into contact with one of the second movable members to allow this second movable member to move to move away from the other second movable member by acting against a restoring force of

  second tension spring means.

  The first booster assembly and the second booster assembly are similar to each other except that the first two movable members move in the first horizontal direction and the two second movable members move in the second direction. horizontal perpendicular to the first

horizontal direction.

  In the floor system of the invention, if the floor moves in a back-and-forth motion in the horizontal direction in the first horizontal direction due to the vibration of a floor

  earthquake, the first mobile elements of the first

  Against the return force of the first tension spring means are alternately displaced by acting against the return force of the first tension spring means. As a result, a portion of the vibration that tends to be transmitted to the floor is converted into the internal energy of the first tension spring means and stored in the first tension spring means, thereby causing the external force (energy vibration) that tends to be transmitted to the floor is damped to come to a low level. When the earthquake ceases, the floor automatically returns to its initial position under a restoring force of the first tension spring means. Even if the floor moves in the second horizontal direction perpendicular to

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  the first horizontal direction, it is still possible to damp this external force, which tends to be transmitted to the floor, to come to a low level and, when the earthquake ceases, the floor can automatically return to the initial position under the recall force of the second recall set. As can be seen from the explanation above,

  since the respective return device of the floor of the invention

  the first set of callbacks and the second set

  even if the tension spring means are damaged.

  In one of the booster sets, the other booster set still performs its full seismic isolation function and therefore the entire booster is never failing to perform a seismic isolation function. In other words, the system of

  the floor of this invention can provide an excellent isolating function.

  earthquake with high reliability.

  In addition, since the first return assembly and the second return assembly are separate from each other in the return device, it is possible to independently install the first return assembly and the second return assembly. Since both the peripheral portion of the floor may be provided with the first return assembly and the second return assembly which form part of the respective return device, if a rotational force is transmitted to the floor from the outside. , it can be effectively suppressed by the first set of booster and the second set

recall.

  In the floor system of this invention, the respective components can be manufactured in compact form, since the return device is separate from the support means and the return device divides into the first return assembly and the As a result, the floor system of this invention can be of low height and it is

  therefore possible to reduce the height between the foundation and the floor.

  FIG. 1 is a schematic side view showing

  a floor system according to a first embodiment

of this invention.

  Figure 2 is a sectional view taken along

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the line II-II of FIG.

  FIG. 3 is a sectional view showing a device

recall.

  Figure 4 is a partial view, in perspective, showing the return device. Figures 5 to 7 are explanatory views of the

  function of the respective return devices.

  Fig. 8 is a plan view showing a device

  of a second embodiment of this invention.

  FIG. 9 is a partial view, in perspective,

  showing the return device of Figure 8.

  Fig. 10 is a sectional view showing a sectional view as indicated by X in Fig. 9; Fig. 11 is a plan view showing a device

  of a third embodiment of this invention.

  Fig. 12 is a plan view showing a device

  reminder of a fourth embodiment; and the. FIG. 13 is a sectional view showing the device

recall of Figure 12.

  Figures I and 2 show a floor system for seismic isolation according to a first embodiment of this

  invention. The floor system, if roughly divided,

  a floor 14 for supporting, for seismic isolation, an object O disposed above a foundation 12 of a dwelling or a building, to a number of supports 16 disposed between the floor 14 and the foundation 12 and supporting the floor 14 so that it can be

  move in a horizontal direction, and a number of

  restoring devices 18 arranged between the foundation 12 and the floor 14.

  In Figure 2 is shown only a single reminder

  18 disposed at an angle of the floor 12.

  The respective supports 16 are arranged in a matrix as shown in FIG. 2. The respective support 16

  comprises a flat plate 20 fixed to the upper surface of the base

  12, an upright 22 mounted on the bottom surface of the floor 14 and a number of balls or rollers attached to the end

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  lower the amount so as to roll on the flat plate 20. The return devices 18 comprise a first return assembly 26 and a second return assembly 28 of the same construction. For convenience, only one of the first booster set and the second booster set will be explained here. The first

  return assembly 26 is arranged on the outer peripheral portion

  the first return assembly 26 comprises an elongated base plate 30, as shown in Figures 3 and 4, attached to the upper surface of the foundation 12. A pair of guide members 32, 34 are coaxially attached each to each end portion of the upper surface of the base plate 30. The respective guide members 32 and 34 each comprise a flat section 36 attached to the base plate 30 and two folded sections 40 which define a pair of guide grooves 38, 38 which are mutually

  face, along the longitudinal axis of the flat section 36.

  respective buckets 42, 44 are mounted on the guide members 32, 34 to slidably move along the longitudinal axis of the guide members. The slats 42, 44 each have a plate section 46 of a size allowing on its sides a slidably accommodating, in the groove 38, a first projecting wall 48 provided at the end of the slab section away from the slab medium. the base plate 30 and extending in the direction

  of the floor 14, a buffer 50 provided on the inner surface of the first

  projecting wall 48 and a second projecting wall 52 provided at the other

  end of the plate 46 located near the middle of the base plate.

  noting that the second projecting wall 52 is lower than the first

  The sliders 42, 44 are connected to each other via a pair of helical tension springs 54 which extend in a parallel direction. To further explain the tension coil springs 54, the two ends of the tension coil springs 54, 54 are anchored to screws 56 which

  extend respectively through the second projecting walls 52.

  The screws are fixed, by corresponding nuts 58, to the seconds

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  projecting walls 52 of the slides 42, 44. Consequently, the length, and therefore the restoring force, of the coil tension springs 54 can be adjusted by turning the nuts on the screws 56. For example, four stops 60 are fixed on the upper surface of the base plate 30 to prevent the slides 42 and 44 from being able to move

  towards each other within a predetermined distance.

  Two contact members 62, 62 are attached to the bottom surface of the floor 14, as shown in FIG. 3, and extend downwardly so that the first projecting wall 48, carrying the buffer 50, can abut against the contact element 62. In this regard, it should be noted that the width of the contact element 62 is

  determined to ensure the contact of the projecting wall 48 with the element

  contact 62, even if the floor moves in one direction

  perpendicular to the longitudinal axis of the return device.

  The second booster set 28 has the same structure as the first booster set. Therefore we use the same

  reference numerals to designate the parts or elements corresponding to

  to those indicated in the first recall set and

  avoid a new explanation to be shorter.

  The second return assembly 28 is, like the first return assembly 26, disposed at the peripheral portion of the floor 14 with its longitudinal axis placed perpendicular to that of the

first set of booster 26.

  The mode of operation of the seismic isolation floor system according to the first embodiment of this invention will be explained below in connection with the first return assembly 26 of the return device 18 and with reference to FIGS. there is no external vibration, as an earthquake to transmit to the foundation 12, the first projecting walls 48, carrying the buffer 50, abut against the respective contact elements 62 and the slides 42, 44, abut against the

  respective abutments 60, 60 under a restoring force of the helical springs.

  voltage gauge 54 as shown in FIG. 5. That is, the floor 14 is maintained in an initial position as z2572446

shown in Figure 5.

  If in this state, a vibration acts on the foundation 12 in the direction of an arrow P of Figure 6 to cause the foundation 12 to move in the direction of the arrow P of Figure 6, the slide 44 located in a the direction opposite to the direction of the arrow P is slidably driven by the floor 14 in said opposite direction, (i.e., as the floor 14 tends to remain in its initial position despite the displacement of the foundation 12, the first projecting wall 48 of the slider 44 is pushed by the contact element 62 of the floor 14, via its

  buffer 50, causing the slider 44 to move in the said direction

  the opposite direction by acting against the return force of the coil springs

  The result is that a part of the vibration force that can be transmitted to the floor 14 is stored in the form of an extension force of the tension coil springs 54. That is to say that the vibration effectively transmitted to the floor 14 is reduced to a lower level, which allows the first return assembly 26 to provide a better seismic isolation function. When the earthquake ceases and therefore no vibration is no longer transmitted to the floor 14, the floor 14 is automatically returned to its initial position at the same time as the coulhsseaux 44, under a restoring force of the helical tension springs 54, If, on the other hand, the foundation 12 undergoes vibrations in a direction perpendicular to the direction of the arrow P, it is the second return assembly 28, situated in a direction perpendicular to that of the first return assembly 26, which, like the first return assembly 26, allows the floor 14 to perform seismic isolation functions and automatic return to its original position. Since the return device 18 comprises the first call assembly 26 and the second return assembly 28, whose restoring forces act in mutually perpendicular relation, it allows the floor 14 to effectively provide the seismic isolation and return functions.

  automatic in both horizontal direction.

  Because the return device 18 includes the first return assembly 26 and the second return assembly 28, it is possible to effectively remove a rotational force even if it acts on the floor 14 in the horizontal direction. In other words, because the first recall set 26 and the second

  recall assembly 28 are both placed at the peripheral portion

  In the floor 14, the tension coil springs 54 of the first return assembly 26 and the second return assembly 28 can be effectively used to suppress the rotational force acting on the floor.

on the floor 14.

  In addition, the return device 18 and the support 16 which supports, with the possibility of displacement, the floor 14 are provided separately from one another and, in addition, the return device 18, in itself, is also divided in the first return assembly and the second return assembly, thereby providing a compact arrangement of the floor system components. As a result, a smaller gap between the foundation 12 and the floor 14 is sufficient and therefore there is no need for a larger dwelling or building. No adverse effect of a certain importance is exerted on the return device 18 even if one of the springs 54 of the return assembly 26 breaks in service. This may also be true, although limited to a certain extent, of the case where the two helical tension springs 54 break, since the other return assembly 28 allows the floor 14 to perform to a certain extent the function seismic isolation. Accordingly, the floor system of this invention provides a reliable seismic isolation function with respect to installed appliances or equipment.

on the floor 14.

  Since the tension loads of the coil tension springs of the first return assembly 26 and the second return assembly 28 can be easily adjusted, it is possible to

  easily adjust the minimum acceleration that - applies to the floor-

  14 when the floor 14 begins to move under vibration.

  This point is continued with reference to FIG. 7 where the abscissae indicate a displacement of the floor 14 and the ordinates indicate the load applied to the floor. Let's consider for the

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  moment that the first set of reminder 26. In this case if A repre-

  feel an acceleration that will apply to the movable member which is on the side of the floor 14, (the movable member includes the floor

  14), this floor must not move unless it satisfies the conditions

  following: A0 O> (F0 + Ffr) / m with FO: preloading of the tension coil springs 54 defined by giving an initial tension to the tension coil springs 54 of the first return assembly Ffr: static friction force of the element mobile on the face of the floor; and

  m total mass of the moving element. -

  If K and 'represent a total elasticity constant of the coil springs 54 of the first return assembly and the elongation of the coil tension springs 54, the following condition must be satisfied: mA K + Ffr to make the movable element ( floor 14) rests against the foundation 12 even if this mobile element receives an acceleration AI greater than the acceleration A0. From this equation, the elongation of the coil springs 54 = (mA Ffr) / K can be deduced below. That is, if the coil tension springs 54 are lengthened by a value - this easily adjust the AI acceleration for which

  the movable element (floor 14) begins to move.

  This invention is not limited to the floor system

  for seismic isolation according to the first embodiment of the invention.

  Figures 8 to 10 show a first return assembly 26 and a second return assembly 28 in a return device 18 of a seismic isolation floor system according to a second embodiment of this invention. The same reference numerals are used to designate parts or elements corresponding to those shown in FIGS. 3 to 4.

  a new explanation, except for what is said below.

-35

13 2572446 The first recall set 26 and the second recall set 28 of the

  second embodiment comprise two sliders 72, 74 of a bottomless box-shaped configuration. The slides 72 and 74 comprise a box section 78 of such a size that it is housed between two guide elements 76, 76 and two core elements 80, 80 which extend horizontally in the direction of the guide elements. 76, 76 and sandwiched between a base plate 30 and the corresponding guide member 76. The box section 78 includes a first projecting wall 48 and a second projecting wall 52 and two side plates which connect the first projecting wall 48 at the second projecting wall

  52. In the second embodiment, a respective support plate is provided.

  82 having one end extending through the second projecting wall 52 and attaching to the lower portion of the first projecting wall 48 and the box section 78 and the other end extending in the direction of the other slide. In the second embodiment of this invention, stops for the slides 72 and 74 are each attached to the upper surface of the base plate 30 so that each abuts against the lower portion of the first wall.

  protrusion 48 of the slides 72 and 74.

  The support plates 82 provided on the sliders

  72, 74 are connected together via a thermal damper

  84. At the front end of the plate 82, on the side of the

  slide 72, is fixed an outer cylinder 86 of the hydraulic damper

  84, its axis extending parallel to the tension coil springs 54. A rod 90 extends coaxially through an inner cylinder 88 of the hydraulic damper 84 and a rectangular frame 92 is attached to the front end of the rod. 90. Two buffers 94 are mounted on the inner surface of the frame 92. On the other hand, projections 96 are attached to the end portion of the support plate 82, on the side of the slide 72. The projection 96 is housed in frame 92 leaving free a space L so that it can slide

  in the direction in which the sliders 72 and 74 move.

  A buffer 98 is attached to the projection 96 so as to come in front of the

buffer 94 of the frame 92.

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  It is obvious that even in the first return assembly 26 and in the second return assembly 28 of the second embodiment, the same results as in the first embodiment can also be obtained. If one, 74, sliders moves to move away from the other slide 72, a distance exceeding the distance (gap) L, the hydraulic damper 84 is extended so as to provide a damping function. That is, if the amplitude whose floor 14 moves relative to the foundation 12, exceeds the distance L, the hydraulic damper 84 provides the damping function, thus eliminating the displacement of the floor 14 to bring it back to a low value and provide an ideal seismic isolation function. Fig. 11 shows a booster assembly of a third embodiment of this invention which includes hydraulic dampers 84 between the respective sliders 72, 74 and a baseplate 30. That is, the respective hydraulic damper 84 has its outer cylinder 86 fixed to a base plate 30 and its inner cylinder coupled to a frame 92 via a rod 90. A protrusion 96, which protrudes on the upper surface of a support plate 82, is housed in the frame 92 so as to slide relative to the frame, noting that the support plate 82 is mounted only on the underside of the slide. It goes without saying that the booster assembly is constructed so that the respective hydraulic damper

  84 performs the same function as in the second embodiment.

  Figures 12 and 13 show a recall assembly of a fourth embodiment of this invention which comprises hydraulic dampers 84 arranged between the sliders 72 and 74. That is to say that each hydraulic damper 84 has its cylinder

  86 exterior connected, each to the other. At the same time, the cylinder

  88 and hydraulic dampers 84 are coupled to the sliders 72, 74 respectively. In the embodiment of FIGS. 12 and 13, the hydraulic cylinders 84 are arranged between the slides 72 and

  74, and a single hydraulic cylinder can be used.

  Although in the respective embodiments, two coil tension springs are incorporated in the booster assemblies

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  respective, a single coil spring of tension or more than two helical springs can be used. In addition one can use other

  types of dampers instead of the hydraulic damper.

  In the embodiments mentioned above, the return device 18 is disposed on the foundation 12 with the contact element 62 attached to the lower surface of the floor, n but can be arranged on the lower surface of the floor with the element of contact 62

attached to the foundation 12.

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Claims (3)

CLAIMS I. Floor system for seismic isolation comprising a floor (14) disposed above a fonation with a space left between them and on which is disposed an object which must be isolated by damping the seismic effects; support means (16) for supporting the floor so that the floor can move in a horizontal direction; and a number of return devices (18) located between the foundation and the floor and provided for, when the floor has moved in the horizontal direction from its initial position relative to the foundation, to produce a force return button to allow the floor to return to its initial position characterized in that the return device comprises a first return assembly and a second return assembly (26, 28); said first return assembly (26) comprising (a) a pair of first movable members (42, 44, 72, 74) disposed on one of the two, the top surface of the foundation and the bottom surface of the floor which will move to move closer and away from each other in a first horizontal direction; (b) first stops (60) to prevent the first two movable members from moving within a predetermined distance in the direction of each other; (c) first tension spring means for connecting the first two movable members to each other; and - (d) a first contact element (62) provided on the other of the two, the upper surface of said foundation and the lower surface of the floor, and adapted for, if the floor moves in the first horizontal direction relative to said foundation, contacting one of the first movable elements to cause said one of the first movable elements to move apart. 17 2572446   on the other of the first movable elements acting against a restoring force of the first tension spring means (54); said second return assembly (28) comprising (a) a pair of second movable members (42, 44, 72, 74) disposed on one of the two, the upper surface of said foundation and the lower surface of the floor, and which will move to move toward and away from each other in a second horizontal direction perpendicular to the first horizontal direction; (b) second stops (60) to prevent the second movable elements from moving within a predetermined distance in the direction of each other; (c) second tension spring means (54) for connecting the two second movable members to each other and (d) second contact members (60) on the other of the two of the surface top of the foundation and bottom surface of the floor, and provided for, if the floor moves relative to the foundation in the second horizontal direction, come   in contact with the second movable element to enable it to   the other second moving element by acting against a surface   return of the second means forming a tension spring.   A seismic isolation floor system according to claim 1, characterized in that the support means comprises a number of supports (16), each of which comprises a plate (20) attached to the foundation, an amount (22) provided on the bottom surface of the floor (14) and extending towards the plate (20), and at least one ball (24) mounted at the lower end of the upright   so as to roll on the plate (24).   A floor system for seismic isolation, according to claim 1, characterized in that the first tension spring means and the second tension spring means of the first return assembly and the second return assembly (26, 28) comprise each at least one helical tension spring (54). 18 2572446   A seismic isolation floor system according to claim 3, characterized in that first tension spring means and the second tension spring means of the first return assembly and the second return assembly (26, 28) comprise means setting to adjust the length of the   helical tension spring (54).   5. Floor system for seismic isolation according to   claim 4, characterized in that the adjustment means comprise   a screw (56) connected to at least one end of the helical tension spring (54) and movably attached relative to the movable member in an axial direction, and a nut (58) for securing the screw (56) to the movable member; 6. floor system for seismic isolation, according to claim 1 characterized in that the first set of recall   and the second return assembly (26, 28) are mounted on the foundation.   Floor system for seismic isolation according to claim 6, characterized in that the first return assembly and the second return assembly (26, 28) further comprise guide elements (30, 36, 38, 40, 76) fixed to the foundation for slidingly guiding the first movable element and the second movable element in said first horizontal direction and said second movable element. horizontal direction.   8. System & floor for seismic isolation according to claim 6, characterized in that the first movable element and the second movable element of the first return assembly and the second return assembly comprise a wall (48) projecting towards the lower surface of the floor; and in that the contact elements of the first booster assembly and the second set of   recess comprise a contact plate (62) attached to the lower surface   the floor to allow it to abut against the projecting wall (48). Floor system for seismic isolation according to claim 8, characterized in that a buffer (50) is mounted between the corresponding abutment surfaces of the projecting wall (48).   and said contact plate (62). 19 2572446   10. floor system for seismic isolation according to claim 1, characterized in that it further comprises damping means (84) located between the upper surface of the foundation. and the floor.   11. seismic isolation floor system according to claim 1, characterized in that the first return assembly and the second return assembly further comprise means   damping means (84) between the pair of movable members. -   12. Floor system for seismic isolation, according to claim 1, characterized in that the first return assembly and the second return assembly further comprise - damping means (84) for limiting a displacement of the moving elements when their elements movers move to depart one of   the other beyond a predetermined distance.   13. Floor system for seismic isolation according to claim 12, characterized in that the damping elements   comprise a hydraulic damper comprising an outer cylinder   a frame (92) coupled to an inner cylinder (88) of the hydraulic damper, and a member (96) provided in the other movable and adjusted member - in the frame so as to be able to move in a direction of movement of the movable element.